Mechanism for controlling the aiming of ordnance



2 Sheets-Sheet 1 G. A. CROWTHER INVENTOii Geo eAZfred Crowflwr MECHANISMFOR CONTROLLING THE AIMING 0F ORDNANCEI July 10. 1956 Filed May 26, 19575Q Z; 2:-,4Jfiw4 H|$ ATTORNEY July 10, 1956 CRQWTHER 2,754,058

MECHANISM FOR CONTROLLING THE AIMING OF ORDNANCE Filed lay 26, 1937 2Sheets-Sheet 2 SIGHT ANGLE (MINUTES) llllllllllllllllll RANGE (YARDS)TIMEOFFLIGHT(SECONDS) llllllllllllllllllll RANGE (YARDS) CHANGE OF RANGE(YARDS) TIME OF FLIGHT (sacouos) INVENTOR GeorgeALfraZ Crowilwr HISATTORNEY United States Patent MECHANISM FOR CONTROLLING THE AIMING OFORDNAN CE George Alfred Crowther, Manhasset, N. Y., assignor to SperryRand Corporation, a corporation of Delaware Application May 26, 1937,Serial No. 144,849

6 Claims. (Cl. 235-615) My invention provides means for continuouslygenerating present range values and for correcting these values toobtain gun ranges and the corresponding sight angles includingcorrections for such prediction factors as relative movement of thetarget and the eifect of the apparent wind during the time of flight ofthe projectile, and which also allow for the effect of ballistic factorsdue to various particular initial velocities and to an initial velocityloss therefrom.

When a gun of a given calibre is new it causes a projectile to leave itsmuzzle with a certain initial velocity, and this condition substantiallyprevails for a prescribed number of rounds the gun is fired. Thereafter,there is a diminution in the initial velocity of the projectile due togun erosion. There are also other contributory causes such as variancesin powder temperature, barometric pressure and projectilecharacteristics which afiect the initial velocity of the projectile.

The purpose of the herein described initial velocity loss rangecorrector is to calculate a range correction which will modify the valueof a sight angle such that when the deteriorated gun is elevated inaccordance with this angle it will have an elevation for a fictitiousadvance range which will include compensation for the loss in theinitial velocity of the projectile.

The novel features include means for converting the evaluations of thetime of flight of the projectile for corresponding range values tocorresponding range corrections for an arbitrary or unit initialvelocity loss, and then proportionally converting the range correctionfor the unit initial velocity loss to the range correction for theactual initial velocity loss. A further object is to effect the additionof the thus obtained range correction for the actual initial velocityloss to the range prediction due to the change in range during the timeof flight. It is a con tinuing purpose to add the sum so efieeted to thepresent range of the target to secure the gun or advance range and toconvert the advance range to a sight angle such that when thedeteriorated gun is elevated in accordance with the so determined sightangle the trajectory of the projectile will be compensated for itsactual initial velocity loss.

The invention will be understood from the following description inconnection with the accompanying drawings in which Fig. l is a diagramof a system embodying my invention;

Figs. 2, 3 and 4 are diagrams showing graphically the function ofcertain mechanisms in the apparatus.

In using the computing apparatus as a whole, and particularly as shownin Fig. 1, a crank 1 is operated to introduce the initial or observedrange obtained from a suitable source, as a range finder. The side 2 ofa differential D-9 is connected to the crank 1 and the center 2" of adifferential D-9 is thereby positioned in accordance with the existingor initial observed range. This value is generally known as presentrange. From the center 2" the value of the range is transmitted by adrive 3 to 2,754,058 Patented July 10, 1956 another drive 4, which, inone direction extends to and actuates a present range counter 5. Goingalso in another direction drive 4 turns a side 6' of a diiferential D-10proportionately to the value of the present range as indicated by thepresent range counter 5.

From known calculating means the required values of quantities necessaryto certain computations to be performed by the apparatus are available.These calculating means are settable in accordance with the estimatedcourse and speed of the target and the known course and speed of ownship, as well as the direction and velocity of the Wind, both of whichare known through'suitable means for measuring them. In consequence ofthe above referred to settings, the known calculating means determinethe values of the component of the range rate due to the targetsmovement, YT, the component of the range rate due to own ships movement,Y0, and the component of the eifect of the wind in the direction of therange, Yw.

The total range rate, dR, due to the relative movement of the target andown ship, may be ascertained from any of a number of well known means,and may be introduced into the present computing apparatus by a handcrank 7, or automatically from a suitable source of its calculation. Infact, the range rate may, if desired, be obtained from the abovereferred to known calculating means which determines the values of thequantities YT and Y0, since the range rate, dR=YT+YO.

Operated by the hand crank 7, a drive 8 actuates another drive 9, apinion 10, which shifts a rack 11 and a ball carriage containing balls12 in accordance with the range rate, dR, the balls being shiftedradially of a disk 13. A constant speed motor 14 operable in accordancewith time acts through a drive 15 and a pinion 16 meshing with thetoothed periphery of the disk 13 to rotate this disk uniformly accordingto time. The position of the balls 12 radially of the disk 13 representsthe range rate, dR, which is multiplied by the rotation of the disk, theconsequent revolution of the balls 12 rotating an output roller 17 inaccordance with the change of range AR. The output roller 17 operates adrive 18 and side 2" of difierential D-9 whereby the center 2" ofdifferential D-9 and the drive 3 continuously operate drive 4, presentrange counter 5 and side 6 of differential D-10 in accordance with theinstantaneous or generated value of the present range R.

Consideration of the use of the present range, R, will now be held inabeyance while the calculation of the range prediction that is added toit is discussed.

As previously stated, the range rate, dR equals (Yr-+Yo), and expressedas (Yr+Yo) is transmitted to a side 19' of a differential D-24. Also,the range component due to own ships movement, Yo, and the rangecomponent due to the effect of wind in the direction of the range, Yw,are added to give the apparent wind component in range, WR, which isintroduced into the present computing apparatus either by the hand crank20, or automatically, to operate a drive 21. Drive 21 operates gearing22 which has a-ratio which supplies a constant K1, by which the quantityWR, is multiplied, the product being regarded as K1(Yo+Yw) which istransmitted from gearing 22 to the center 19" of differential D-24. Twoneeded quantities, RT and Rw may now be obtained, of which Rr=range ratedue to the range components of movement of the target and the own ship,multiplied by the time of flight; and

Rw=the total efiect of the wind in the direction of range upon theprojectile during the time of flight.

The formulae for these equations are:

RW=-WR(K1TK2) =(Yo-l-YW) (-K1T|-K2) (2) Where Yr-l-Yo: range rate, dR;T=time of flight; WR=total apparent wind in range Yo-l-Yw); and K1 andK2 are constants.

RT and Rw are computed simultaneously in the range predictor, KIWR beingsubtracted from dR in differential D-24, and their differenceconstituting a factor which is introduced into the range predictor whereit is multiplied by the time of flight, T, to give a product, which,when the quantity KzWn is added thereto becomes the range predictionuncorrected for initial velocity loss, Rrw.

For a more ready comprehension of these mathematical operations thedetermination of RT and Rw will be undertaken separately, and with rangerate, dR, expressed as (YT-I-YQ), and the total effect of the wind inrange, WR, as (Yo-I-Yw).

In determining the value of RT, the measure of the range rate (YT+ Yo)is applied, as already stated, to side 19' of differential D-24 to betransmitted through its other side 19", a drive 23 and a pinion 24 to aninput sector 25 of the range predictor 26 to angularly displace thissector in accordance with the value of the factor (YT+Yo). Rotatablymounted on sector 25 is a screw shaft 27, which is turned in accordancewith the time of flight, T, derived from a source to be subsequentlydescribed. A block 28 is slidable in a radial slot 29 in sector 25, theslot being substantially coextensive with the screw shaft. As the screwshaft 27 is threaded through the block 28 and has no longitudinaldisplacement, the block acts as a traveling nut on which a pin 30 isrigidly mounted. Pin 30 projects through an elongated slot in a crossbar 31 of a link 32 which is pivotally connected at one end to a pivotedarm 33 and at its other end to pivoted output sector 34. This effects aparallel motion of the pivoted arm 33 and the output sector 34 dependentfor its magnitude upon the combined displacements of input sector 25 andthe block-carried pin 30 as moved in response to the turning of thescrew shaft 27. Such displacements produce an approximate multiplicationof the range rate (YT-I- Yo) by the time of flight, T. The movement ofthe output sector 34 resulting from the above described operationscorresponds to the product of the above mentioned multiplication, whichis RT.

Superimposed upon the multiplication set forth above is anothermultiplication required in the determination of the value of thequantity Rw, which compensates for the effect of the wind in thedirection of the range during the time of flight. Since the hereinbeforedescribed operation of the center 19" of differential D-24 in accordancewith the value of -K1(Yo+Yw) is transmitted through the side 19" of thedifferential and by drive 23 and pinion 24 to the input sector 25, whichmay now be regarded as being displaced according to the value of-K1(Yo+Yw). This factor is multiplied in the previously described mannerby the time of flight, T, which has already been shown to be introducedin the range predictor 26 as another factor. Therefore, in the phase ofthe operation now under consideration, the output sector 34 is displacedin accordance with K1T(Yo|-Yw), the value of which is transmitted fromthis output sector by a pinion 35 and a drive 36 to the center 37" of adifferential D-26. However, from Formula 2 it is seen that the quantityK2(Yo+YW) must be added to K1T(Yo+YW) in order to determine the value ofthe quantity Rw. To accomplish this there is a branch drive 38 drivenfrom drive 21 in accordance with (Yo+YW) to gearing 39 which has a ratiothat effects a multiplication the product of which gives the quantityK2(Yo+Yw). A continuing drive 40 transmits the quantity K2(Yo+YW) fromthe gearing 39 to the side 37' of differential D-26 where it isalgebraically added to --K1T(Yo+YW) to give The composite effect of thetwo simultaneous multiplications set forth above causes the outputsector 34 of the range predictor 26 to actually be displaceable inaccordance with the value of a quantity which is designated Raw, and thealgebraic addition thereto in differential D-26 of the quantityK2(Yo+YW) changes the value of R'rw' to that of Raw, which is A rangecorrection for the initial velocity loss of the projectile due to gunerosion and other contributory causes is computed and combined with therange prediction, R'rw, already determined. Inasmuch as the computationof the range correction for the initial velocity loss, Rv, is somewhatinvolved and requires the determination of the value of the advancerange, R2, it will be easier, at first, to recognize that rangecorrection for the initial velocity loss, Rv, is effected by mechanismto be described hereinafter to be available for combination with therange prediction, R'rw, obtained as shown above.

Proceeding along these lines, it is clear from what has gone before thatthe output side 37 of differential D-26 is operable in accordance withthe value of the range prediction, R'rw, and operates a drive 41 and adial 42 which reads against a fixed index to give a reading of the valueof the range prediction, R'rw. Drive 41 displaces a side 43 and thecenter 43" of a differential D-13 to move the pivoted contact arm 44into engagement with one or the other of a pair of fixed contacts 45 ofa follow-up switch, according to whether the value of the rangeprediction is increasing or decreasing. Thereupon current flows from onemain 46 of a current supply line by conductors 47 and 48 to the contactarm 44, the engaged fixed contact 45, one of a pair of conductors 49(shown as a single line), through the normally engaged blades of acut-out switch 50 to a motor 51 designated as the R'rwv motor. Thecurrent returns from this motor by conductors 52 and 53, two normallyengaged and flexed blades 54 and 55 of a multiple-motor cut-out switchand conductor 56 to the other main 58 of the current supply line.

The R'rwv motor 51 is, therefore, energized and runs to operate a drive59 which in turn operates another drive 60 that extends in oppositedirections. In one direction the drive 60 goes to and actuates the side61' of a differential D-12 in accordance with the value of the quantityRTWV, which is the sum of the range prediction Raw and the rangecorrection for the initial velocity loss, Rv. The center 61 ofdifferential D-12 is operated in accordance with the quantity Rv, whichis subtracted in differential D-12 from R'rwv which is introduced by theside 61. This subtraction prevents the contact arm 44 of the follow-upswitch from becoming dissociated with the contact 45 it has engageduntil the RTwv motor 51 has run an amount equal to the combined valuesof the range prediction RTW and the range correction for the initialvelocity loss, Rv. The subtraction also takes the quantity Rv from thequantity R'rwv, leaving the quantity RTW, which is the value of therange prediction. The quantity R'rw as obtained from the subtraction istransmitted by a drive 62 from the side 61" of differential D-12 to theother side 43" of differential D-13. Therefore, the operation of side43" in accordance with R'rw will match the in ut of Raw at side 43' asreceived from side 37" of differential D-26, when the R'rwv motor 51 hasrun an amount corresponding to the sum of Raw and Rv, i. e., inaccordance with the quanttiy R'rwv.

Now, since the RTWV motor 51 operates drives 59 and 60 in accordancewith the quantity R'rwv, the drive 60 duced by the hand crank 64 whichturns a drive 65, which sets a dial 66 against a fixed index to indicatethe value of the present correction of this nature, drive 65 alsooperating the side 63 of differential D-11. The result is that the rangespot correction, JR, is added to the sum of the range prediction, Raw,and the range correction for the initial velocity loss, Rv. Theconsequent actuation of the side 63" of differential D-11 gives thetotal summation of these quantities, which is the complete rangeprediction, designated as RJTwv. Differential side 63" transmits thecomplete range prediction, RJTWV, by a drive 67 to the side 6" ofdifferential D- where it is added to the present range, R, that waspreviously shown to be carried to the side 6' of this differential.Consequently, the center 6" of differential D-10 is operated inaccordance with the value of the advance range, R2, and actuates drives68 and 69 to operate a counter 70 to give a reading of the value of theadvance range.

The advance range drive 68 continues to another drive 71 which includesgearing 72 having a ratio that multiplies the advance range, R2, by aconstant K3 to get KsRz, which effects the conversion of the advancerange, R2, to a straight line approximation of the sight angle, Us. Theadvance range drive 68 also extends to a worm gear 73 that drives a wormwheel 74 fast on a shaft 75. Also rigidly mounted on shaft 75 is aplurality of sight angle complement cams 76, 77 and 78, each of whichfurnishes the complement or correction to the straight lineapproximations of the sight angle Us in accordance with a par ticularforce of the powder charge to be used in the gun. For example, cam 76may be for a powder charge of a given strength that causes theprojectile to have a particular initial velocity as it leaves the muzzleof the gun. Cams 77 and 78 are for other individually different powdercharges each effecting a particularly different initial velocity of theprojectile. Obviously the sight angle, Us, varies for the variousinitial velocities, and is used in further computation.

Fig. 2 shows three curves plotted against advance range, i. e., thesight angle plotted against advance range, R2, whereby for each curvethe difference between the straight line approximation of and the actualsight angle is obtained for different ranges thus determining thecontour of each of the three sight angle complement cams. In Fig. 2 a, band c are the curves for cams 76, 77 and 78, respectively. It will onlybe necessary to consider the curve a, as curves b and c are utilized inthe same Way. The hereinbefore referred to drive 71 continues from thegearing 72 that supplies the constant K3, which converts the advancerange R2 to the straight line approximation of the sight angle, Us,toextend to and operate the side 79 of a differential D-101 inaccordance with such approximation.

This straight line approximation is indicated in Fig. 2 by the straightline a. The shaded area between the straight line d and the curve 11represents the complement Use supplied by the contour of the cam 76,which displaces the roller and the follower 80, so turning a squareshaft 81 and sector 82 in accordance with the value of the sight anglecomplement, Usc. Sector 82 thus actuates a pinion 83 and a drive 84 toturn the center 79" of differential D-101 in correspondence with thesight angle complement Use, which is algebraically added to the straightline approximation of the sight angle. Accordingly, the other side 79"of differential D-101 is operated to give the value of the actual sightangle, Us, for the particular advance range, R2, existing at the time.

Side 79" of differential D-101 operates a drive 85 and the side 86' andcenter 86" of another differential D-100 in accordance with theevaluation of the sight angle, Us, thereby displacing the pivotedcontact arm 87 of a follow-up switch to engage one or the other of apair of fixed contacts 88.

As a result, current will flow from the main 46 of the current supplyline by conductors 47 and 89 to the contact arm 87 and the engaged fixedcontact 88 and through one of a pair of conductors 90 (shown as a singleline) to and through the mutually engaged contact blades of a cut-outswitch 91 and therefrom to a sight angle, Us, motor 92. From this motorthe current returns by conductors 93, 53, the normally engaged blades 54and 55 of the multiple-motor cut-out switch, and conductor 56, to theother main 58 of the current supply line. The sight angle, Us, motor 92will therefore be energized and run.

The Us motor will accordingly operate drives 95 and 96 to actuate acounter 97 to cause it to give a reading of the value of the sightangle, Us. In case of any failure of the Us motor 92, such value may beintroduced manually by lifting a spring pressed pin 98 out of theannular groove of a collar 99 into which it is shown in Fig. 1 to beentered, and longitudinally shifting a shaft 99' on which the collar isaffixed until a second annular groove is aligned with the pin 98. Themanual retracting grip on the pin is then released and the springpressure on the pin enters the latter into the second annular groove,holding shaft 99 in new axial position. Shaft 99' is so shifted by amanual thrust exerted on a hand crank 100 attached thereto. Thisshifting operation carries a gear 101 frictionally attached to shaft 99'for rotation therewith into mesh with another gear 102 fast on a shaft103 that is connected to drive 96 to operate it as the hand crank 100 isturned to manually introduce the value of the sight angle, Us. When theshaft 99 is moved longitudinally in the described manner, its oppositeend pushes the longer of the normally engaged blades of cut-out switch91 out of contact wtih the shorter of these blades, thus opening thecircuit through the Us motor 92. Hence, this motor will be deenergizedwhen the sight angle, Us, is introduced manually.

Another drive 104 is connected with drives 95 and 96 so as to beoperable by either the Us motor 92 or the Us hand crank 100. Drive 104operates a further drive 105 which actuates the other side 86" ofdifferential D-100 and the center 86" thereof to return the contact arm87 to its neutral position, thus opening the circuit through the Usmotor 92 when it has run an amount-corresponding to the value of thesight angle, Us, which has been introduced by the side 86 of thedifferential.

This value of the sight angle, Us, is also transmitted from drive 104 toanother drive 106, which operates gearing 107 that has a ratio thatmultiplies the value of the sight angle, Us, by a constant K4 which is acoefiicient that converts the sight angle, Us, to an approximation T ofthe time of flight. From the gearing 107 the drive 106 continues to andoperates the side 108 of a differ- 'ential D-108 in accordance with thevalue of the approximation of the time of flight.

To obtain the complement of the time of flight, To, any one of cams 109,110 and 111 is employed according to the chosen strength of any of anumber of powder charges, each of which produces a particular initialvelocity of the projectile for a given gun. The time of flightcomplement cams 109, 110 and 111 are used similarly to the manner inwhich the sight angle complement camsl 76, 77 and 78 are utilized, andare rigidly mounted on a shaft 112, which also has a worm gear 113attached thereto and which is in mesh with a worm 114 also operated bythe drive 68.

Referring to Fig. 3, the curves 2, f and g represent an pproximation,T', of time of flight plotted against advance range, R2, for thedifferent initial velocities resulting from the use of the differentpowder charges. Curves, h, i and j represent the actual time of flight,T, plotted against R2. The difference between the ordinates for theapproximate time of flight, T, and the actual time of flight, T,represented by the shaded portion, is the time of flight complement, To.To therefore represents the quantity which must be added to theapproximation, T, to produce the exact value, 'T.

It will be suflicient to consider merely related curves e and h, and tosay that the shaded area between these curves gives the value of thetime of flight complement, To, in accordance with which the contour ofthe time of flight complement cam 109 is shaped. This cam acting on theroller of the follower 115 causes the squared shaft 116 and the sector117 attached thereto to turn proportionately to the value of the time offlight complement, To, which is transmitted by the pinion 118 and drive119 to the center 108" of differential D-108. Hence, the time of flightcomplement, To, is added to the approximation of the time of flight, T,in accordance with which the differential side 108' is actuated wherebythe other side 108" of this differential is operable according to theactual time of flight, T.

To adapt the computing mechanisms to either of the other initialvelocities, an initial velocity knob 120 is first moved to the rightfrom the position shown in Fig. 1. This effects an axial sliding of ashaft 121 and a cylindrical rack 122 on the opposite end thereof.Cylindrical rack 122, therefore, turns a pinion 123 in mesh with it, ashaft 124 carrying the pinion and another pinion 125 aflixed to theshaft. Pinion 125 consequently displaces a flat rack 126 and a shift bar127 to which it is attached. Lugs 128 fast on shift bar 127 engage andturn levers 129 secured to the upper ends of the square shafts 81 and116, so turning these shafts and the followers 80 and 115 carriedthereby whereby the followers are angularly displaced to be clear of allof the cams with which the followers are associable.

Shaft 121 in being axially displaced slides through a gear 130 that isjournaled in a bifurcated bracket 131 and is provided with a keyway sothat the initial velocity knob 120 may be turned, after the followers810 and 115 have been positioned to clear the cams to which they arerelated. Knob 120 turns shaft 121, which by virtue of its keyway and akey drives gear 130 and another gear 132 in mesh therewith to operatedrives 133, 134 and 135 and flexible driving connections 136 which turnscrewshafts 137 that are threaded through the cam followers 80 and 115.These followers are, therefore, moved parallel to the axes of rotationof the sight angle complement and time of flight complement cams intoassociation with such of these cams as are for the particular initialvelocity to be conformed to. Knowledge that cam followers have beenaligned with the proper cams is had from the reading of an initialvelocity dial 138 against a fixed index, this dial being operated fromdrive 133 by a drive 139.

The initial velocity knob 120, shaft 121 and cylindrical rack 122 arethen pushed in the reverse direction, moving the shift bar 127 also inthe reverse direction. Shift bear lugs 128 are thus moved out of the wayof the levers 129, which are pulled by springs 140 so as to turnreversely the square shafts 81 and 116 thus turning the cam followerscooperatively to engage the perimeters of the cams for the selectedinitial velocity.

When the shift bar 127 is moved to clear the cam followers of the cams,as described above, another lug 141 is also moved with it allowing theflexed contact blades 54 and 55 to straighten out, under which conditionthese blades become disengaged. This opens the circuits through thevarious motors so that they become deenergized during the period whenthe cam followers are shifted from certain cams to other cams, as willbe more fully explained later on.

Also, as the shaft 121 is shifted axially, it is prevented from beingsubjected to abrupt starting, stopping and other shocks by a hydraulicretarder 142, which is suitably connected by an arm 143 with the shaft121.

It has been shown that the approximation of the time of flight, T, andthe time of flight complement, T0, were combined in dilferential D-108so that the computed value of the actual time of flight, T, became theoutput of side 108" of this differential. Side 108" operates a drive 144and a side 145' and center 145" of a differential D-109, the centerturning a pivoted contact arm 146 to engage one or the other of a pairof fixed contacts 147 of a follow-up switch.

Thereupon current will flow from the main 46 of the current supply byconductors 47 and 148 to the contact arm 146, through the engaged fixedcontact 147 and one of a pair of conductors 149 (shown as a single line)through normally mutually engaged blades of a motor cut-out switch 150and therefrom to a time of flight, T, motor 151. Returning from thismotor the current goes by conductors 152, 52 and 53, blades 54 and 55 ofthe multiple-motor cut-out switch, and conductor 56 to the other main 58of the current supply line. The motor 151 will, therefore, run inaccordance with the time of flight, T. In so doing, it operates drives153, 154 and 155 to operate a counter 156 to give a reading of the timeof flight, T. Drive 154 continues to and operates the screw shaft 27 ofthe multiplier termed the range predictor 26, the driving of which shafthas been earlier referred to.

Furthermore, it has been explained that the center 61' of differentialD-12 is operated in correspondence to a range correction, Rv, which isdirectly proportional to the amount of the initial velocity loss, butwith no explanation as to how such correction is obtained. This will nowbe set forth. A prediction of the range correction for an arbitraryinitial velocity loss, designated Rv', is calculated, and this loss maybe taken as 200 feet per second initial velocity loss.

When the time of flight motor 151 is running, as explained, it operatesdrive 153 thereby actuating a portion of drive 154 that extends to andoperates another drive 157 which includes gearing 158 that has a ratiowhich produces a coetncient that constitutes a constant K5. Constant K5multiplies the time of flight, T, to obtain a straight lineapproximation of the change of range for the arbitrary initial velocityloss. Continuing from the gearing 158, the drive 157 operates a side 159of a differential D-102 according to the value of the straight lineapproximation of the change of range for the arbitrary initial velocityloss.

In Fig. 4 the straight line approximation of the change of range for theunit or arbitrary initial velocity loss is represented by the straightline k, which is plotted against time of flight at appropriate scales.The remainder, Rv'c, of the range correction, Rv', for the arbitraryinitial velocity loss is the difference between the straight lineapproximation denoted by the line k and the actual value indicated bythe line I plotted against the two mentioned quantities at the samescale. Therefore, the shaded area between the straight line k and thecurve I along the ordinate representing the change of range for theparticular value of the time of flight evaluates the remainder, Rv'c,that must be added to the straight line approximation of the rangecorrection, Rv', for the arbitrary initial velocity loss.

To secure the remainder, Rvc, of the range correction Rv', a cam groove160 is laid out on a rotatable peripherially toothed cam disk 161 incorrespondence with the variance of the range correction complement,Rv'c, which varies as a function of the time of flight, T. The drive 157that is operable proportionately to the time of flight, T, also extendsto a pinion 162 which turns the cam disk 161 in accordance with the timeof flight, T. As the cam disk so turns it displaces a pin 163 that isentered into the cam groove 160, the pin being a rigid part of a camfollower which further consists of a sector 164 that is pivoted at 165.The toothed arcuate part of the sector 164 operates a pinion 166 and adrive 167 which operates the center 159" of differential D-102 incorrespondence with the value of the component Rvc. Thus, the componentRv'c is added to the straight line approximation of the range correctionintroduced by the differential side 159' whereby the other side 159 isoperable proportionately to the range correction for the arbitraryinitial velocity loss, Rv'. By the hereinbefore described means, thetime of flight is converted to the change of range during the time offlight for an arbitrary initial velocity loss.

Operation of the side 159", as described, actuates a drive 168 and apinion 169, which angularly displaces a pivoted sector 170 of what maybe termed an initial velocity loss corrector 171. Thus, the rangecorrection for the arbitrary initial velocity loss, Rv, is introducedinto this corrector where it is multiplied by the actual initialvelocity loss, the multiplying mechanism being so designed that theproduct Rv will bear the same proportion to Rv' that the actual initialvelocity loss bears to the arbitrary initial velocity loss. To introducethe actual initial velocity loss a retaining pin 172 urged into aholding position by a spring is raised to remove it from the annulargroove in a collar 173 in which it is entered, the collar being fast onan axially shiftable shaft 174. An initial velocity loss knob 175 isthen pulled out so axially shifting shaft 174 to mesh a gear 176 thereonwith another gear 177. The retaining pin 172 is then released and entersa second groove in collar 173 to hold the gears in mesh. Thereafter theinitial velocity loss knob 175 is turned to rotate shaft 174, gears 176and 177 and a drive 178 which turns a dial 179, causing it to readagainst a fixed index and it is graduated to show the correspondinginitial velocity loss. This value is accordingly transmitted from drive178 by another drive 180 to a screw shaft 181 that is rotatably mountedon the sector 170 of the initial velocity loss corrector 171. Screwshaft 181 displaces a traveling nut 182 having a rigid pin 183 thatextends into a slot in a cross bar 184 of a link 185 which at one end ispivotally connected to a pivoted arm 186. The other end of link 185 issimilarly connected to a pivoted output sector 187, which is thus movedin parallelism with the arm 186 with a magnitude dependent upon thecombined displacements of input sector 170 and pin 183. Thesedisplacements effect the multiplication of the range correction for thearbitrary initial velocity loss, Rv, by the actual initial velocityloss. Hence, the resultant product, as represented by the movement ofthe output sector 187 is the range correction for the actual initialvelocity loss, Rv. It is now apparent that, in addition to the presenceof means for converting the time of flight to the change of range duringthe time of flight for an arbitrary initial velocity loss, there arealso means for multiplying such change of range by the proportionbetween the arbitrary and actual velocity loss.

Displacement of sector 187 in accordance with the range correction forthe actual velocity loss, Rv, transmits this quantity by a pinion 188and a drive 189 to the center 61" of difierential D-12, where it isutilized as hereinbefore set forth to become included in the completerange prediction, RJTWV, and to be subtracted from the quantity Rrwv,forming part of the range prediction, to obtain the output quantity,R'rw, that matches the input quantity, R'rw, whereby the operation ofthe R'rwv motor 51 is controlled. Drive 189 actuates another drive 190and a dial 191 so that the latter reads against a fixed index to give areading of the range correction for the entire initial velocity loss,Rv.

Should the R'rwv and the time of flight motors 51 and 151, respectively,fail for any reason, the mechanism of the former may be operated by amanual control device 192 and the latter by another manual controldevice 193. Each is in all respects similar to the device 98-102 formanually controlling the sight angle, Us, mechanism and operates in thesame way.

It is obvious that various modifications may be made in the constructionshown in the drawings and above particularly described within theprinciple and scope of my invention.

I claim:

1. In mechanism for determining data for use in controlling the aimingof ordnance, means actuated by a range settable member for computing thecorresponding time of flight of a projectile for a particular initialvelocity, means actuated by the time of flight computing means todetermine the corresponding change of range of the projectile due to anarbitrary initial velocity loss from the particular initial velocity,and multiplying means having one input member actuated by the change ofrange determining means and a second input member actuated in accordancewith the actual initial velocity loss for multiplying the said change ofrange by the proportion between the said arbitrary velocity loss and theactual initial velocity loss.

2. In mechanism for determining data for use in controlling the aimingof ordnance, means positionable in accordance with present range, meansfor initially positioning said present range means, means settable inaccordance with the rate of change of range, integrating means having arate member positioned by said rate settable means, means actuated bythe increments of range obtained from the integrating means tocontinuously position the present range positionable means, meanspositionable to represent the time of flight of a projectile,multiplying means actuated by said rate settable means and by the timeof flight positionable means to position an output member in accordancewith the change of range during the time of flight, means actuated bythe time of flight positionable means to position an element inaccordance with the corresponding change of range due to an arbitraryinitial velocity loss, second multiplying means actuated by the elementand in accordance with the proportion between the arbitrary initialvelocity loss and an actual initial velocity loss to position an outputmember in accordance with the change of range for the actual velocityloss, means actuated in accordance with the position of the output ofthe first mentioned multiplying means and the present range positionablemeans to position a member in accordance with the advance range,means'for modifying the position of the advance range member inaccordance with the position of the output member of the secondmultiplying means, and means actuated by the advance range member toposition the time of flight positionable means.

3. In mechanism for determining data for use in controlling the aimingof ordnance, the combination of means actuated in accordance with thetime of flight of a projectile for determining the corresponding rangecorrection due to an arbitrary initial velocity loss, proportional meansfor converting the said range correction to a range correction for anactual initial velocity loss, mechanism operated in accordance with thetime of flight of the projectile for determining a range prediction dueto the change of range during the time of flight, means jointly operatedby the mechanismand the proportional means for positioning an element inaccordance with the range prediction combined with the range correctiondue to the actual velocity loss, means positionable in accordance withthe present range of a target, differential means controlled by theelement and the range positionable means to position a member inaccordance with the corresponding advance range, and apparatus actuatedby said member for determining the sight angle and time of flightcorresponding to the advance range.

4. In mechanism for determining data for use in controlling the aimingof ordnance, the combination comprising means actuated in accordancewith the time of flight of a projectile for computing a correspondingrange correction due to an arbitrary loss of initial velocity, andmultiplying means having one input member actuated by said computingmeans, a second input member actuated in accordance with the actual lossof initial velocity and an output member positioned thereby to representthe range correction corresponding to the actual loss of initialvelocity.

5. In mechanism for determinig data for use in controlling the aiming ofordnance, the combination comprising/means positionable in accordancewith the range to a target, means actuated thereby for computing acorresponding range correction due to an arbitrary loss of initialvelocity, multiplying means having one input member actuated by saidcomputing means, a second input member actuated in accordance with theactual loss of initial velocity and an output member positioned therebyto represent the range correction corresponding to the actual loss ofinitial velocity, and means actuated by the output member of themultiplying means for 10 modifying the position of the rangepositionable means.

6. Mechanism for determining data for use in controlling the aiming ofordnance, comprising means settable in accordance with the present rangeof a target, means for positioning a member in accordance with thecorrection to be combined with the present range to give the advancerange, said positioning means including mechanism for computing therange correction due to relative movement of the target during the timeof flight, means for computing the range correction due to the effect ofwind on a projectile, and means for computing the range correction dueto initial velocity loss, means for determining advance range includingdifferential means actuated in accordance with the positions of therange settable means and the member to position an element to representthe advance range, and means actuated by the element for converting theadvance range to the corresponding sight angle.

References Cited in the file of this patent UNITED STATES PATENTS1,453,104 Gray Apr. 24, 1923 1,811,688 Gray June 23, 1931 1,904,215 FordApr. 18, 1933 1,999,368 Myers Apr. 30, 1935

